Weiss Helios Wins Stereophile Class A+ Recommended Component

Processors from this Swiss company have consistently performed well, not just on the test bench but also in the listening room.
In the August 2020 issue, I concluded that review by writing ‘The Weiss DAC502 retrieves more information from the digits than any other DAC I have auditioned. Notably, that superb transparency to the recorded data was not accompanied by glare or exaggerated treble. The DAC502 cleaned the window into the recorded soundstage to an impressive extent.’
The Helios echoed the DAC502’s extraordinary clarity but with an enhanced sense of involvement with the music.
The clarity of the soundstage was just as superb, as I remember from my first time with the DAC502. This was particularly evident on Rufus Reid Presents Caelan Cardello. Reid’s round-toned double bass and Cardello’s Fazioli piano were palpably present in the rather dry club acoustic, the instruments superbly well-defined in both space and tonal balance.
I finished my listening with Dunedin Consorts’ Hodie Christus natus est a 8. The sparse arrangement was laid meticulously clear by the Helios, each singer presented stably in the stereo image. I was intending to audition just this one track but I ended up listening to the entire album. I didn’t quite get up to dance – but it was a close-run thing.
Today it isn’t necessary to choose [between Accuracy or Musicality]: The Weiss Helios shows you can have both.
Channel separation was superb at >122dB. The level of random noise is extremely low, and there are no AC supply related spuriae present. Reducing the maximum level didn’t increase the level of the noisefloor.
Even at the lowest level, the amplitude error is <1.1db, which implies very high resolution. An increase in bit depth from 16 to 24 dropped the Helios’s noisefloor by 33dB. This implies a resolution between 21 and 22 bits, which is the highest I have encountered, greater than even the Weiss Helios DAC502.
With undithered 24-bit data, the Helios’s very low analog noisefloor means it can output a clean sinewave, even at this very low signal level.
Weiss’s DAC502 performed supremely well on the test bench, but its measured performance was exceeded by that of the Weiss Helios!
John Atkinson, Stereophile March 2024,
Stereophile Class A+ Recommended Component, April 2024